Maybe for the first part, i.e. some animal viruses have the ability to infect humans, but usually lack sufficient capabilities to then go on to infect other humans from a human host.

Edit: I am not saying this was done in a lab. It can happen naturally as well, for example this happened with the swine-flu. But it usually requires prolonged and wide-spread close contact between humans and these animals, which is unlikely in the case of cave bats.